A 3-D velocity measurement was carried out via LDV for vortex breakdown of swirling flow in a closed cylindrical container with a rotating disk. The experimental results of swirling flow at Ar=1.78 and Re=648-2527 are...A 3-D velocity measurement was carried out via LDV for vortex breakdown of swirling flow in a closed cylindrical container with a rotating disk. The experimental results of swirling flow at Ar=1.78 and Re=648-2527 are presented. At the axis, the axial velocity variation with Re describes the formation, development and disappearance of the vortex breakdown, which agrees with Escudiers's conclusion. In the meridional plane, the velocity vectors show that the bubble type vortex breakdown region is a closed and low velocity circulating flow, which is fully isolated from the main flow thrown out by the rotating disk. For the peripheral velocity in the central region of the container, the maximum does not appear near the rotating top disk but near the stationary bottom disk and it varies sharply there. Numerical simulation results under the same conditions are also given in this paper.展开更多
The method of composite porous media with mini-longitudinal channels at the surface and with heads packing between plates was put forward to improve the integrated performance of flow and heat transfer in porous media...The method of composite porous media with mini-longitudinal channels at the surface and with heads packing between plates was put forward to improve the integrated performance of flow and heat transfer in porous media. The experimental results in the corresponding porous media were reported and analyzed. The experiments indicate that with proper matching of the particle diameter dp, the mini-channel width ω, the channel depth d and the distance between plates δr the heat transfer in the composite porous media is enhanced and flow resistance reduced compared with those of no mini-longitudinal channels at the surface. So this is an effective method to improve the integrated performance of flow and heat transfer in porous media.展开更多
文摘A 3-D velocity measurement was carried out via LDV for vortex breakdown of swirling flow in a closed cylindrical container with a rotating disk. The experimental results of swirling flow at Ar=1.78 and Re=648-2527 are presented. At the axis, the axial velocity variation with Re describes the formation, development and disappearance of the vortex breakdown, which agrees with Escudiers's conclusion. In the meridional plane, the velocity vectors show that the bubble type vortex breakdown region is a closed and low velocity circulating flow, which is fully isolated from the main flow thrown out by the rotating disk. For the peripheral velocity in the central region of the container, the maximum does not appear near the rotating top disk but near the stationary bottom disk and it varies sharply there. Numerical simulation results under the same conditions are also given in this paper.
文摘The method of composite porous media with mini-longitudinal channels at the surface and with heads packing between plates was put forward to improve the integrated performance of flow and heat transfer in porous media. The experimental results in the corresponding porous media were reported and analyzed. The experiments indicate that with proper matching of the particle diameter dp, the mini-channel width ω, the channel depth d and the distance between plates δr the heat transfer in the composite porous media is enhanced and flow resistance reduced compared with those of no mini-longitudinal channels at the surface. So this is an effective method to improve the integrated performance of flow and heat transfer in porous media.
